It is well known that photographic processing solutions need to be replenished periodically in photographic processing apparatus to maintain constant sensitometry for the material being processed. Replenishment is made to the processing solutions so that their chemical composition and activity are kept within specified limits to maintain sensitometry for the material being processed.
Replenishment of photographic solutions is dependent on the area of the material being processed. However, this is not the sole dependency. Normally, other factors are also considered to effect complete replenishment. The present invention is applicable to replenishment which is dependent on the area of material being processed assuming that an average exposure has been given to the material.
In most processing apparatus, the area of material being processed is determined by measuring the length of the material being processed by mechanical or optical means assuming that the material has a fixed width. Additionally, if the width of the material is not fixed, the width may also be measured using suitable means, for example, infrared sensors positioned across the width of the entry slot to the processing apparatus.
Once the area of the material being processed has been determined, replenisher solutions are then pumped into the appropriate processing tank or tanks at a rate related to that area to effect replenishment.